Suggestions for creating a good book...
Erase every game plan play but one and copy and paste it to every scenario so there is only one play in your game LAN. Then, erase every play in the book except that one play and four others. Now, save it and those five plays will lock in as your five audibles.
Use a base book that does not have the formations you plan on putting into it. That way you can sort of control your form audibles. Just don't add any plays you don't want as form audibles. Once you add a play, if it is chosen as a form audible - if you take it out, it will leave an empty spot in your form audibles. As long as your patient though, it gives you control over your form aubibles. For instance, the CPU recognizes screens as PA - so if you add no true PA plays, you will have a screen as your PA form audible in that set. It also gives you reason to add a few sets where you only have a few plays. For instance, if a draw is your only run out of a certain set - it will be your run form audible by default. If you add in a set that was already in the default book than it already has form audibles set for that set. So, be sure to have these plays in so you don't have holes in your form audibles. This is why it's better to not use a playbook with your favorite sets because you can create the set better from scratch.
Lastly, set your play books as default play books in your settings. If you set them to custom play books, you will get booted from online games before the team select screen, you can switch your play books to your custom ones without an issue. I think the game tries to read the roster and the play books at the same time if you have custom play books selected before the team selection screen and it boots you from EA's servers.